Create 'change' operation on collection for a specific object.

[matt-filion]

Applies only to an existing object, fails if none found.
Argument takes in a function to manipulate the loaded object.
eTag matching used to reject the change if the object is modified 'underneath' the change.
If rejected, re-attempts the operation 3 times.
If fails 3 times then fails completely.
Object is re-loaded for each attempt with the current eTag.